A musical note or tone produced by a musical instrument of string, piano or percussion types is characterized by an envelope having a relatively rapid rise time and a relatively slow, usually exponential, fall or decay time. If an insolated musical note signal of the aforementioned type were recorded, as with a tape recorder and then played backwards, there would result a highly unusual and pleasing note signal having a slow rise and a rapid decay. Of course, however, music is composed of a sequence of notes and playing a prerecorded musical program backwards would yield the sequence of notes in backwards order. Similarly, if this recorder and its associated speaker were in motion and were accellerating toward the listener, the apparent frequency of a note signal would steadily increase during the duration of the signal. This latter effect would also occur if the playback speed of the recording were steadily increasing.